A file is a data structure for storing data using a file-system on a data storage device. Some examples of the data storage devices (storage devices) on which file-systems are constructed include magnetic hard disk drives and tape drives, flash memory cards and other solid-state data storage devices, and optical data storage devices.
When an application requests a file, the file is loaded from the storage device into a working memory (memory). To enable this loading, reading, and writing of data to the storage device, the file data is stored on the storage device in blocks (pages) of a fixed size (page size). For example, data storage blocks in a particular configuration may be 64 Kilobytes (KB) in size, with a file's data being stored in one or more of such blocks.
A file-system being used, an operating system under which the file-system executes, a memory manager, or a combination thereof define the size of blocks used to store files in the file-system. The file-system keeps track of the blocks that comprise a file. As and when a file is requested, the blocks where the data of the requested file is stored are identified by the file-system, and some or all of the blocks storing the data of a file are loaded from, read from, or written to the storage device.